computer: Hold Git credentials on the host with an auth resolver

[mattzcarey]

The Git commands the model runs, the worker-shell git command and ws:git, have no way to authenticate (#218). Host code can pass headers or onAuth on each typed call, but a model running git push against a private repository has to put a token on the command line, where it ends up in the transcript.

createGitClient() now takes an auth resolver. The client calls it for every HTTPS request a clone, fetch, pull, or push makes. It passes the repository URL and whether the request reads (fetch) or writes (push), then adds whatever credentials come back as an Authorization header:

const ws = new Workspace({
  storage: ctx.storage,
  git: createGitClient({
    auth: ({ url, operation }) =>
      url.startsWith("https://github.com/acme/")
        ? { username: "x-access-token", password: env.GITHUB_TOKEN }
        : undefined,
  }),
});

The resolver wraps the HTTP transport rather than each command. That way the typed API, cli(), the shell's git command and ws:git all get it, because the last two already run through the host's Git client. The token never reaches argv, the remote URL, .git/config or the output. Knowing the operation lets a host hand out a read-only token for fetches and a write token for pushes, for example short-lived Artifacts tokens.

An Authorization header passed on a call wins, and the resolver isn't asked. Plain http:// requests never get credentials.

The new auth.test.ts covers the header shapes and the operation detection. It also checks that call headers win, that plain HTTP gets nothing, and UTF-8 encoding. It drives a real Workspace through a typed clone, a CLI clone (checking the token isn't in the output) and a CLI push, using a transport that records requests and answers 401. Run it with:

npm test --workspace @cloudflare/computer -- src/git/auth.test.ts

The auth section of docs/13_git_interface.md and the README's Git section describe the resolver. A minor changeset is included.

Not covered here, and possible follow-ups from the issue:

• ls-remote isn't a CLI command yet.
• A redirect to another host relies on fetch dropping the Authorization header across origins.
• The resolver doesn't store secrets. Where tokens live is up to the host.

[changeset-bot]

🦋 Changeset detected

Latest commit: 5b92ccd

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@cloudflare/computer	Minor
@cloudflare/dofs	Minor
@cloudflare/computer-rpc	Minor
@cloudflare/computerd	Minor

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commit: 5b92ccd